Question: $ { {-5} \times \left[\begin{array}{rrr}{3} & {-1} & {4} \\ {-2} & {1} & {2}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{-5}\times{3} & {-5}\times{-1} & {-5}\times{4} \\ {-5}\times{-2} & {-5}\times{1} & {-5}\times{2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{-15} & {5} & {-20} \\ {10} & {-5} & {-10}\end{array}\right]}$